The official Pokémon movie website has updated. Translations follow:

"Pocket Monsters the Movie: I Choose You" Will Come With An Audio Guide for the Visually Impaired!

This time, "Pocket Monsters the Movie: I Choose You" will come with an audio guide for the visually impaired.
The audio guide makes use of the new "UDCast" system.
Those with mobile devices like smartphones, iPod Touch etc. that have the system's app installed can enjoy the movie with the audio guide at all theaters and all screening times.

Planned availability date for the audio guide: Saturday July 29th, 2017
Please note that the audio guide can not be used prior to the above availability date.

In addition, a Japanese subtitled version of the movie for the hearing-impaired will be screened at certain theaters for a limited period. The schedule can be found here once it's been decided.

Some models of some Android devices are not compatible with "UDCast", so make sure it works ahead of time.
*A detailed explanation and user manual for "UDCast" can be found here.
*A list of theaters screening the movie can be found here.

For UDCast customer support:
Palabra,Inc
Telephone: 0120-291-088 FAX: 03-5937-2233
E-mail address: [email protected]

Source: http://www.pokemon-movie.jp/news/?p=2687